Torsional vibration dampers are employed extensively in internal combustion engines to reduce torsional vibrations delivered to rotatable shafts. The torsional vibrations may have a considerable amplitude and, if not abated, can potentially damage gears or similar structures attached to the rotatable shaft and cause fatigue failure of the rotatable shaft. Torsional vibration dampers absorb vibration and, to a certain extent, reduce the amplitude of the vibrations by converting the vibrational energy to thermal energy as a result of the damping action. The absorption of the vibrational energy lowers the strength requirements of the rotatable shaft and, therefore, lowers the required weight of the shaft. The torsional vibration damper also has a direct effect on inhibiting vibration of nearby components of the internal combustion engine which would be affected by the vibration.
Virtually all motor vehicles with internal combustion engines incorporate a “serpentine” drive belt system consisting of a single endless drive belt and a series of pulleys. The pulleys derive power from the endless drive belt and operate to drive the various vehicle accessories such as the engine fan, power steering pump, air pumps, air conditioning unit, and the alternator. The endless drive belt that drives each of these pulleys is driven by a drive pulley connected to the crankshaft of the internal combustion engine. To reduce the transfer of vibrations between the crankshaft and the serpentine drive belt system, the drive pulley may comprise a torsional vibration damper that functions to absorb vibration and reduce the amplitude or magnitude of the angular vibrations delivered by the crankshaft.
With torsional vibration dampers it is generally desirable to maximize the inertia within the space permitted. Typically, torsional vibration dampers rely on an annular inertia member that rests on an elastomeric ring compressed between the inertia ring and a hub. With such a design, if one is to replace the rubber component, one must remove the damper from the crankshaft of the engine. This is relatively labor intensive. Further, with this design, assembly is problematic. The elastomer must be compressed during assembly of the damper. This requires special equipment which, in turn, increases the cost of the damper.